The present invention relates to an automatic machine for the welding of metallic parts which one desires to assemble. More precisely the invention relates to a machine operated by a programmable control device and capable of carrying out "in situ" welds along a profile common to the parts to be assembled and comprising at least one curvilinear portion.
One has already proposed various automatic machines permitting to assemble through welding at least two metallic parts along a common profile. In general each machine comprises a support stationary with respect to the parts to be assembled and on which a robot or carriage is mounted and guided along a "feed" path of travel. A suitable welding equipment forms part of the machine and in particular comprises a torch apt to provide weld points and/or weld beads. The torch itself is movably mounted and guided on the carriage whereas a displacement system is provided to drive the torch as well as the carriage in their guiding directions or paths of travel with respect to the stationary support. Means for the detection of the position of the torch with respect to the parts as well as a programmable control device controlling the displacement system and the welding equipment are provided in the machine. The control device is connected to the detection means and determines as a function of the information supplied by the latter each displacement of the torch in order that a weld be performed along the common profile of the parts.
However, the welding machines of the prior art frequently use mechanical contact sensors (such as feelers, followers etc . . .) to detect and adjust the position of the welding torch. Therefore and above all in the case where this welding is entirely automatic and where the profile comprises curvilinear portions, the machines of the prior art prove themselves to be relatively inaccurate and do not permit to quickly obtain a quality weld. Moreover most of the known welding machines are heavy and cumbersome, so that they are difficult to be used for the welding of parts on the spot or "in situ", i.e. at the very position where these parts will be used.